Tungsten carbide and other hard metals and hard materials have been used extensively since the middle of World War II as a cutting material in production machines. Initially, indexable inserts had an elongate form adjustably supported in a toolholder so that the insert could be reground and moved upwardly to the cutting position. At times chip breaker grooves were ground into the top surface of the insert. The evolution of the industry was such that the so-called elongate or slug-type inserts which needed to be reground were for the most part replaced by rather thin, wafer-like, indexable inserts which were called throw-away inserts because of the fact that once they were used for a certain period of time, they were then discarded rather than reground. In connection with inserts of this kind and even with the earlier high speed steel inserts, it was known to utilize chip breakers positioned adjustably on the top of the cutting inserts and clamped in place. Examples of this type of chip breaker insert are found in the U.S. Pat. to Moore, U.S. Pat. No. 2,181,023, dated Nov. 21, 1939; Richard U.S. Pat. No. 2,870,523, dated Jan. 27, 1959; and Dowd U.S. Pat. No. 3,137,917, dated Jan. 23, 1964.
Other variations of the clamping of chip breakers on the top of inserts are found in the pertinent art.
In many instances, the chip breaker function has been achieved in throwaway inserts by grinding in or molding in a chip breaker groove inside the cutting edge as evidenced, for example, by the above-referenced Dowd patent and more recently by a U.S. patent to Kelm, U.S. Pat. No. 3,341,920, dated Sept. 19, 1967. A U.S. patent to McCreery and Jones, U.S. Pat. No. 3,973,307, dated Aug. 10, 1976, shows a drop center insert.
The present invention contemplates an improvement on the previous structures in the form of an insert which is provided with a ridge or dike around the periphery to present the cutting edge and also to retain a chip breaker insert as well as a support anvil for use in single and multiple toolholding means such as single point toolholders, boring bars, and milling cutters.
The object is to provide an insert with protection for both the top and the bottom and which can be utilized both for negative rake and positive rake cutting edges and one which is more independent of the feed rate and the rotation rate of the work.
The improved design provides satisfactory chip control over a broad range of depth of cut in rotation and it has the advantage that it can be used either with or without the separate mechanical chip breaker. In addition, it can be utilized for not only indexing but also inverting and indexing for all of the cutting sides on each surface, these being protected by the support anvil in operation.
Other objects and features of the invention will be apparent in the following description and claims in which the principles of operation of the invention are set forth together with details of construction and operation which will enable a person skilled in the art to practice the invention, all in connection with the best mode presently contemplated for the construction of the device.